Selection of microplastics by Nile Red staining increases environmental sample throughput by micro-Raman spectroscopy

Nile Red staining enables visual identification and quantification of fluorescent particles as a proxy to microplastics at low cost and high throughput, including those of small sizes (≥2 μm), when preceded by proper natural organic matter removal, but providing no chemical characterization. On the...

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Bibliographic Details
Published in:The Science of the total environment 2021-08, Vol.783, p.146979-146979, Article 146979
Main Authors: Prata, Joana C., da Costa, João P., Fernandes, António José Silva, da Costa, Florinda Mendes, Duarte, Armando C., Rocha-Santos, Teresa
Format: Article
Language:English
Subjects:
Micro-Raman spectroscopy
Microplastics
Nile red
Staining dyes
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Summary:Nile Red staining enables visual identification and quantification of fluorescent particles as a proxy to microplastics at low cost and high throughput, including those of small sizes (≥2 μm), when preceded by proper natural organic matter removal, but providing no chemical characterization. On the other hand, micro-spectroscopy methods allow chemical characterization of particles based on their spectra, essential for polymer identification, but are costly and time-consuming. This work addresses the combination of both Nile Red staining with micro-Raman spectroscopy for the identification of microplastics. Besides being useful for quantification, Nile Red staining can be advantageously used as an objective criterion for pre-selection of particles for micro-Raman spectroscopy, producing little interference. The use of the 442 nm laser in micro-Raman spectroscopy induces Nile Red luminescence thus allowing to target the specific suspected microplastics when using an orange filter, reducing the number of particles subjected to identification and improving sample throughput. Staining dyes could also be used for mapping suspected microplastics before targeted analysis by micro-Raman spectroscopy. Thus, coupling Nile Red with micro-Raman spectroscopy can be useful to improve time efficiency while using this equipment. [Display omitted] •Nile Red staining improves micro-Raman spectroscopy throughput.•Identification is possible without photobleaching by using the 442 nm laser.•Fluorescent particles can be used as a proxy in the quantification of microplastics.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2021.146979